Electromagnetic braking device



Dec. 9, 1952 DU RQSTU 2,620,900

ELECTROMAGNETIC BRAKING DEVICE Filed July 20, 1948 3 Sheets-Sheet l m mvra/a eo/was L EVESQUE flwi'ogra ATTORNEY Dec. 9, 1952 G. L. DU ROSTU ELECTROMAGNETIC BRAKING DEVICE 3 Sheets-Sh 2 Filed July 20, 1948 Dec. 9, 31952 DU os- 2,620,900

ELECTROMAGNETIC BRAKING DEVICE //v VEN TOR GEORGES L EVE'SQUE 00 I905 ru ATTORNEY Patented Dec. 9, 1952 2 EBEC'ERQMAGNETIGYBBAKING; .DEYICE Rostu;-Paris,iFrance, as-

-=signor to SocieteAnonymeAnd-re Citroen; Paris,

France -.Application J uly20, 1948;.SeniaLNo. 33,777 In France July23, 1947 ZZ'Claims.

A;-great;many' braking devices have. already been-proposed; which are applicable to air-kinds -of-machines-andmore particularly to vehicles.

; As a--rul e,--theyare sodesignedthat they: can safely absorb "the power of the system with which they* are'coupled although frequently they are 3110i? sufiiciently cooled "that they can absorb 1 a considerable excess power overya comparatively long period, for instance; vfor the; purpose. ofconitrolling the speed of an.- automobile coasting on a long down grade.

'Thisinyention aims at providing braking means which make-itpossible tothrowtheengineout of ear while-runningdown grade and at the same "time absp-rb the power without overheating. "The braking means accordance with theginvention --maybe arranged at. any point between the-trans- ;m-i ssion-gearsand the wheels or directly on the '-1atter,-;e:;g.-at'the center of the bralge'drums with whichtheymay be combined.

In :applicants co -pending application, Serial Np;fZ;Q24";filed1QQtDber 26;19i ,.now t 2 ,5'12-,065 dated "June' 20, 1950. there has been described a c1utch which operates by frictional engagement between two sets of rings connected rospectively tothe -driv-ingand driven-partand positioned in the field of a fixed electromagnet of U e n, sur o nd n the-rin s- The present invention relates to a somewhat .similar assembly for use in,' d ecelerating. a. rotary memben-relative to a fiXedmQmber by-fthegfric- :,tion oi a' first set of longitudinally loose magnetic ,;1 netal ringssplined on said rotarymember against 1. a'jurther set of likewise longitudinally looseimag- -netic metal ring splined in said fixed member.

The fixed member consists of an annular yoke which is U-shaped in radial-axial section with the legs of the U approximately parallel to the axis. An electromagnet-energizing coil is housed in the bottom of said U-sectioned yoke. Splined in the inside of the outer leg of said U-sectioned yoke are the said rings carried by the fixed memher, which consequently project inwardly.

The movable member comprises a cup-shaped part the skirt of which extends between the cylindrical legs of the U-sectioned yoke. splined on the outside of said cup-shaped part are the said rings carried thereby and which consequently project outwardly. The rings carried by the movable member are interleaved with the ones carried by the fixed member.

The inner disc and ring are keyed on a hollow shaft concentric with that of the annular U-sectional electromagnet and have channels provided therein to lead the cooling liquid from the hollow 122 'shaftinto the-spaces between therings; through apertures communicating with ';the channelszbe- ,tween the bars on the ring. .The-liquid -is-circuj-latedbythe action of centrifugal forceythe rotatable member acting as awhirler,

- In the operation of the'device the rings en age one another. by. pairs. The flux generated by-the .electromagnet coil is dividedintoas many fractions as there are ringpairs. Considering 'the 10 "flux that enters anyone ring of one set'and' then the related ring of the. other. set, themagn'etic attraction. takes place at. their common: surface. Consequently; 'the'fiux crosses thegap once'in'its path from one ring toithe other. v

' .;Eig;.1.is a sectional viewof a preferred embodimer t of the. invention taken on a lane passing thr u h, the axis of the sam th paces. betwe n the rings. b in ex erated.

L'Eig. 2 j, is ,a sectional 1 view, takengin a plane perpendicular to the axis of rotation of "j the .brake, approximately on the 1ine"IIIIj inlFigJ'l. Ji -s3. is a, persp tive view "which showshow the. various ring sets are. splined respectively" on themoyable and in. the'fixed member respectively, .th fi ure. beingpartly. broken away.

The embodiment of the invention illustrated Hinthe drawings. comprises two setsoi ringsi-Aand B associated. respectively, with .a'fixed member .0

vand .a, movable, .memberD. 'Ihe'fixedmemberp 1s. an annular.,U -sec tioned yokehaying an outer the C1 andan inner leaCz with anannular, space between .theLtwo; legs. .The. movable member; D .is. coaxial. with the .fixedmember .Cwandhasran annular .skirtportiouDi Llthat. extends. into; the

C. The inner face of the outer leg C1 of thefixd member is provided with axially extending ribsor splines E which fit into, and cooperate with, grooves T provided in the outer periphery of the rings A so that the rings A are rotationally fixed relative to the fixed member C while being slid able relative to the fixed member in an axial direction. Similarly, the outer surface of the skirt portion D1 of the movable member D is provided with axially extending ribs or splines F which engage in, and cooperate with, grooves Y provided in the inner peripheries of the rings B so that these ring are caused to rotate with the movable member but are slidable relative to said member in an axial direction. The rings A alternate with the rings B so that the two sets of rings are interleaved with one another. The fixed member C is closed by a removable cover G.

The fixed member C is ferromagnetic. It contains a coil H which is stationary and has suitspace between the legs Q1,.'.C2 ,oi thelfixed member,

able terminals providing for an effective connection with an outside power source. The lines Z show the path of the magnetic flux When the coil H is energized.

The movable member D may or may not be provided with recesses on its plane face and the gap J between the skirt portion D1 of the movable member and the fixed member C is as small as possible in order to minimize the required magnetization current.

The movable member D has a central axially extending stem portion W which fits inside a hollow shaft N which is coaxial with the fixed member C. There is a splined connection between the shaft N and the stem W by means of keys X and corresponding grooves. A packing gland W1 provides a fluid-tight seal between the shaft and stem. A spring K in the hollow shaft N presses against the end of the stem W and thereby tends to move the movable member D toward its outer position, as shown in Fig. 1.

When the coil H is energized, the axially slidable rings A and B are drawn toward the coil, i. e. to the right in Fig. 1, thereby causing the rings to stack up and to be drawn into engagement with one another so that both faces of each ring (except the first and the last) are in engagement with adjacent rings. A conventional stop member U prevents the inner most ring A from being pulled off its splined and a stop member V is provided on the movable member D to limit the movement of the outermost ring B toward the left. The magnetic force also tends to move the movable member D toward the right against the action of the spring K. When the coil is de-energized, the spring K tends to move the movable member D back toward the left so that frictional engagement of the movable member with the rings B assists the normal disengagement of the rings.

A union L is provided through which the oil forced into the device can flow out of the easing while a, bearing M makes the apparatus fluidtight at its opposite end and, at the same time, centers the shaft N on which the member D is keyed.

Oil is led into the device through the hollow shaft N and axial duct in the stem portion W, radial ducts P and ducts Q which run parallel l with the surface of the skirt portion D1 of the movable member D. From the ducts Q, the oil is thrown out through orifices R which communicate with said ducts Q and open into the spaces between the rings A and B for the purpose of cooling the rings.

The device as a whole is mounted rigidly or resiliently within a fixed part S.

The apparatus is associated with any suitable device, such as a. resistor, by means of which it can be switched on or off and the current in the coil H can be controlled so that any desired braking torque is obtained.

What I claim as my invention and desire to secure by Letters Patent is:

1. An electromagnetic braking device which comprises a fixed annular U-sectioned yoke, an energizing coil housed in the bottom of the U, a. hollow rotary shaft mounted coaxial with said yoke, a cup-shaped member comprising a shaft keyed in the free end of said hollow shaft and an apertured skirt portion extending between the legs of said U-sectioned yoke, a set of inwardlyprol'ecting and longitudinally movable flat rings carried by the outer leg of said yoke, a further set of outwardly-projecting and longitudinally movable flat rings carried by the skirt portion of said cup-shaped member and interleaved with the inwardly-projecting rings carried by the outer leg of the yoke, a casing to enclose said yoke together with said cup-shaped member, ducts being provided axially in the shaft, radially in the end wall of the cup-shaped member and longitudinally in the skirt portion of the latter to lead a cooling liquid through apertures in the skirt of the cup-shaped member into the space occupied by said interleaved rings, said casing being provided with an aperture to let out the liquid flowing thereinto from said space.

2. An electromagnetic braking device according to claim 1, in which splines provided on the inside of the outer leg of the U-sectioned yoke cooperate with notches in the outer edges of the first-mentioned set of rings and splines provided on the outside of the skirt portion of the cupshaped member cooperate with notches in the inner edges of the last-mentioned set of rings.

GEORGES LEVESQUE DU ROS'I'U.-

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 854,720 Dawson May 28, 1907 1,271,401 Weydell July 2, 1918 1,746,365 Schunemann Feb. 11, 1930 2,057,876 Berry Oct. 20, 1936 2,267,114 Lear et al. Dec. 23, 1941 

